U.S. patent number 9,983,443 [Application Number 14/801,597] was granted by the patent office on 2018-05-29 for display device.
This patent grant is currently assigned to Samsung Display Co., Ltd.. The grantee listed for this patent is Samsung Display Co., Ltd.. Invention is credited to Sung Hee Hong, Hyung Gi Jung, Hyun-Ho Kang, Jang-Il Kim, Se Jin Kim, Un Byoll Ko, Sei-Yong Park, Yeo Geon Yoon, Seung Jun Yu.
United States Patent |
9,983,443 |
Kim , et al. |
May 29, 2018 |
Display device
Abstract
A display device may include a floating electrode, a
common-voltage electrode, a transistor, and a pixel electrode. The
floating electrode may be electrically floating. The common-voltage
electrode may be electrically connected to a voltage source. The
pixel electrode may be electrically connected to the transistor. A
first portion of the pixel electrode may overlap neither of the
floating electrode and the common-voltage electrode in a direction
perpendicular to at least one of the pixel electrode and an image
display side of the display device. A second portion of the pixel
electrode may overlap the common-voltage electrode. A third portion
of the pixel electrode may overlap the floating electrode.
Inventors: |
Kim; Jang-Il (Asan-si,
KR), Ko; Un Byoll (Yeoju-si, KR), Yoon; Yeo
Geon (Suwon-si, KR), Jung; Hyung Gi (Cheonan-si,
KR), Park; Sei-Yong (Suwon-si, KR), Hong;
Sung Hee (Hwaseong-si, KR), Yu; Seung Jun
(Suwon-si, KR), Kang; Hyun-Ho (Ansan-si,
KR), Kim; Se Jin (Cheonan-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Display Co., Ltd. |
Yongin, Gyeonggi-Do |
N/A |
KR |
|
|
Assignee: |
Samsung Display Co., Ltd.
(KR)
|
Family
ID: |
56367475 |
Appl.
No.: |
14/801,597 |
Filed: |
July 16, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160202564 A1 |
Jul 14, 2016 |
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Foreign Application Priority Data
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Jan 8, 2015 [KR] |
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10-2015-0002980 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F
1/134309 (20130101); G02F 1/136218 (20210101); G02F
1/134345 (20210101); G02F 1/133345 (20130101); G02F
1/133707 (20130101); G02F 1/134381 (20210101) |
Current International
Class: |
G02F
1/1343 (20060101); G02F 1/1337 (20060101); G02F
1/1333 (20060101); G02F 1/1362 (20060101) |
Field of
Search: |
;349/129 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10-0193656 |
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Feb 1999 |
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KR |
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10-2005-0121881 |
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Dec 2005 |
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KR |
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10-2008-0082086 |
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Sep 2008 |
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KR |
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10-2009-0036870 |
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Apr 2009 |
|
KR |
|
Primary Examiner: Chen; Wen-Ying P
Attorney, Agent or Firm: Innovation Counsel LLP
Claims
What is claimed is:
1. A display device comprising: a floating electrode, which is
electrically floating; a common-voltage electrode, which is
electrically connected to a voltage source and encloses an opening;
a transistor; and a pixel electrode, which is electrically
connected to the transistor, wherein a first portion of the pixel
electrode overlaps neither of the floating electrode and the
common-voltage electrode in a direction perpendicular to at least
one of the pixel electrode and an image display side of the display
device and is positioned over the opening in the direction, wherein
a second portion of the pixel electrode overlaps the common-voltage
electrode, and wherein a third portion of the pixel electrode
overlaps the floating electrode, wherein a material of the
common-voltage electrode is identical to a material of the floating
electrode.
2. The display device of claim 1, further comprising: a common
electrode; and a liquid crystal layer, which is positioned between
the pixel electrode and the common electrode, wherein the pixel
electrode is positioned between the liquid crystal layer and the
common-voltage electrode.
3. The display device of claim 1, wherein the common-voltage
electrode is spaced from the transistor in a plan view of the
display device.
4. The display device of claim 1, wherein the floating electrode is
positioned between two portions of the common-voltage
electrode.
5. The display device of claim 1, wherein the third portion of the
pixel electrode overlaps a center portion of the floating
electrode.
6. The display device of claim 1, wherein the third portion of the
pixel electrode overlaps at least two edges of the floating
electrode.
7. The display device of claim 1, wherein the second portion of the
pixel electrode surrounds the first portion of the pixel
electrode.
8. The display device of claim 1, wherein the third portion of the
pixel electrode is positioned closer to the transistor than at
least one of the first portion of the pixel electrode and the
second portion of the pixel electrode.
9. The display device of claim 1, further comprising: a
non-conductive member, which directly contacts each of the floating
electrode and the common-voltage electrode.
10. The display device of claim 9, wherein the non-conductive
member includes at least one of a color filter, a light-blocking
member, and an overcoat.
11. The display device of claim 1, further comprising: a
passivation layer, which directly contacts each of the floating
electrode, the common-voltage electrode, and the pixel
electrode.
12. A display device comprising: a floating electrode, which is
electrically floating; a common-voltage electrode, which is
electrically connected to a voltage source; a transistor; and a
pixel electrode, which is electrically connected to the transistor,
wherein a first portion of the pixel electrode overlaps neither of
the floating electrode and the common-voltage electrode in a
direction perpendicular to at least one of the pixel electrode and
an image display side of the display device, wherein a second
portion of the pixel electrode overlaps the common-voltage
electrode, and wherein a third portion of the pixel electrode
overlaps the floating electrode, wherein the common-voltage
electrode has two slits, and wherein a branch part of the pixel
electrode is positioned between the two slits in a plan view of the
display device.
13. A display device comprising: a floating electrode, which is
electrically floating; a common-voltage electrode, which is
electrically connected to a voltage source; a transistor; a pixel
electrode, which is electrically connected to the transistor,
wherein a first portion of the pixel electrode overlaps neither of
the floating electrode and the common-voltage electrode in a
direction perpendicular to at least one of the pixel electrode and
an image display side of the display device, wherein a second
portion of the pixel electrode overlaps the common-voltage
electrode, and wherein a third portion of the pixel electrode
overlaps the floating electrode; and a passivation layer, which
directly contacts each of the floating electrode, the
common-voltage electrode, and the pixel electrode, wherein a first
portion of the passivation layer overlaps the floating electrode in
the direction, wherein a second portion of the passivation layer is
positioned between the pixel electrode and the common-voltage
electrode in the direction, and wherein a thickness of the first
portion of the passivation layer in the direction is less than a
thickness of the second portion of the passivation layer in the
direction.
14. The display device of claim 13, wherein a third portion of the
passivation layer overlaps the floating electrode in the direction
and is positioned between the first portion of the passivation
layer and the second portion of the passivation layer, wherein the
thickness of the first portion of the passivation layer in the
direction is less than a thickness of the third portion of the
passivation layer in the direction.
15. The display device of claim 14, wherein the thickness of the
third portion of the passivation layer in the direction is less
than the thickness of the second portion of the passivation layer
in the direction.
16. The display device of claim 13, wherein a third portion of the
passivation layer is positioned between the pixel electrode and the
common-voltage electrode and is positioned between the first
portion of the passivation layer and the second portion of the
passivation layer, wherein a thickness of the third portion of the
passivation layer in the direction is less than the thickness of
the second portion of the passivation layer in the direction.
17. The display device of claim 16, wherein the thickness of the
third portion of the passivation layer in the direction is equal to
the thickness of the first portion of the passivation layer in the
direction.
18. The display device of claim 13, wherein a third portion of the
passivation layer overlaps the common-voltage electrode without
overlapping the pixel electrode in the direction and is positioned
between the first portion of the passivation layer and the second
portion of the passivation layer, wherein a thickness of the third
portion of the passivation layer in the direction is less than the
thickness of the second portion of the passivation layer in the
direction.
19. The display device of claim 18, wherein the thickness of the
third portion of the passivation layer in the direction is greater
than or equal to the thickness of the first portion of the
passivation layer in the direction.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority to and the benefit of Korean
Patent Application No. 10-2015-0002980 filed in the Korean
Intellectual Property Office on Jan. 8, 2015; the entire contents
of the Korean Patent Application are incorporated herein by
reference.
BACKGROUND
(a) Field
The present invention is related to a display device, such as a
liquid crystal display device.
(b) Description of the Related Art
Display devices may be used in various electronic devices, such as
computer monitors, televisions, mobile phones, etc. Display devices
may include cathode ray tube display devices, liquid crystal
display devices, plasma display devices, etc.
As an example, a liquid crystal display device may include two
panels with field generating electrodes (such as a pixel electrode
and a common electrode) and may include a liquid crystal layer
interposed between the two panels. The liquid crystal display
device may display an image by applying a voltage to the field
generating electrode to generate an electric field in the liquid
crystal layer. The electric field may determine orientations of
liquid crystal molecules of the liquid crystal layer, for
controlling transmission of light through the liquid crystal
layer.
The above information disclosed in this Background section is for
enhancement of understanding of the background of the invention.
The Background section may contain information that does not form
the prior art that is already known in this country to a person of
ordinary skill in the art.
SUMMARY
An embodiment of the present invention may be related to a display
device. The display device may include a floating electrode, a
common-voltage electrode, a transistor, and a pixel electrode. The
floating electrode may be electrically floating. The common-voltage
electrode may be electrically connected to a voltage source. The
pixel electrode may be electrically connected to the transistor. A
first portion of the pixel electrode may overlap neither of the
floating electrode and the common-voltage electrode in a direction
perpendicular to at least one of the pixel electrode and an image
display side of the display device. A second portion of the pixel
electrode may overlap the common-voltage electrode in the
direction. A third portion of the pixel electrode may overlap the
floating electrode in the direction.
The display device may include a common electrode and a liquid
crystal layer. The liquid crystal layer may be positioned between
the pixel electrode and the common electrode. The pixel electrode
may be positioned between the liquid crystal layer and the
common-voltage electrode.
The common-voltage electrode may be spaced from the transistor in a
plan view of the display device.
A material of the common-voltage electrode may be identical to a
material of the floating electrode.
The floating electrode may be positioned between two portions of
the common-voltage electrode.
The third portion of the pixel electrode may overlap a center
portion of the floating electrode.
The third portion of the pixel electrode may overlap at least two
edges of the floating electrode.
The second portion of the pixel electrode may surround the first
portion of the pixel electrode.
The third portion of the pixel electrode may be positioned closer
to the transistor than at least one of the first portion of the
pixel electrode and the second portion of the pixel electrode.
The common-voltage electrode may have two slits. A branch part of
the pixel electrode may be positioned between the two slits in a
plan view of the display device.
The display device may include a non-conductive member. The
non-conductive member may directly contact each of the floating
electrode and the common-voltage electrode. The non-conductive
member may include at least one of a color filter, a light-blocking
member, and an overcoat.
The display device may include a passivation layer. The passivation
layer may directly contact each of the floating electrode, the
common-voltage electrode, and the pixel electrode.
A first portion of the passivation layer may overlap the floating
electrode in the direction. A second portion of the passivation
layer may be positioned between the pixel electrode and the
common-voltage electrode in the direction. A thickness of the first
portion of the passivation layer in the direction may be less than
a thickness of the second portion of the passivation layer in the
direction.
A third portion of the passivation layer may overlap the floating
electrode in the direction and may be positioned between the first
portion of the passivation layer and the second portion of the
passivation layer. The thickness of the first portion of the
passivation layer in the direction may be less than a thickness of
the third portion of the passivation layer in the direction. The
thickness of the third portion of the passivation layer in the
direction may be less than the thickness of the second portion of
the passivation layer in the direction.
A third portion of the passivation layer may be positioned between
the pixel electrode and the common-voltage electrode and may be
positioned between the first portion of the passivation layer and
the second portion of the passivation layer. A thickness of the
third portion of the passivation layer in the direction may be less
than the thickness of the second portion of the passivation layer
in the direction. The thickness of the third portion of the
passivation layer in the direction may be equal to the thickness of
the first portion of the passivation layer in the direction.
A third portion of the passivation layer may overlap the
common-voltage electrode without overlapping the pixel electrode in
the direction and may be positioned between the first portion of
the passivation layer and the second portion of the passivation
layer. A thickness of the third portion of the passivation layer in
the direction may be less than the thickness of the second portion
of the passivation layer in the direction. The thickness of the
third portion of the passivation layer in the direction may be
greater than or equal to the thickness of the first portion of the
passivation layer in the direction.
An embodiment of the present invention may be related to a liquid
crystal display, which may include the following elements: a first
insulation substrate; a thin film transistor positioned on the
first insulation substrate; a pixel electrode electrically
connected to the thin film transistor; a common-voltage electrode
partially overlapping the pixel electrode; a floating electrode
partially overlapping the pixel electrode; a second insulation
substrate facing and spaced apart from the first insulation
substrate; a common electrode positioned on the second insulation
substrate; and a liquid crystal layer positioned between the first
insulation substrate and the second insulation substrate. The
common-voltage electrode is insulated from the pixel electrode and
may receive a common voltage. The floating electrode is insulated
from the pixel electrode and the common-voltage electrode. A pixel
including the thin film transistor includes a first region where a
portion of the pixel electrode is positioned, a second region where
the pixel electrode overlaps the common-voltage electrode, and a
third region where the floating electrode is positioned. In the
pixel, voltage differences from voltage of the common electrode may
be highest at the first region, medium at the second region, and
lowest at the third region.
The pixel electrode may include first cross stem parts positioned
in the first region and the second region, a plurality of first
fine branch parts extending from the first cross stem parts, and a
connection part positioned in the third region.
The common-voltage electrode may include an opening positioned in
the first region and a plate part positioned in the second
region.
The floating electrode may include a second cross stem part
positioned in the third region and a plurality of second fine
branch parts extending from the second cross stem part.
The common-voltage electrode may substantially surround the
floating electrode.
The connection part may have at least one of a cross-shaped member
and a quadrangle-shaped member. The connection part may overlap the
floating electrode.
The opening may have a rhombus shape.
The plate part may further include a slit, and the slit may overlap
the first fine branch part.
The floating electrode may be in an electrically floating
state.
The thin film transistor may include a gate electrode protruding
from the gate line, a semiconductor layer positioned on the gate
electrode, and a source electrode and a drain electrode positioned
on the semiconductor layer.
The liquid crystal display may further include the following
elements: a first passivation layer positioned on the data line and
the drain electrode; and a second passivation layer positioned on
the common-voltage electrode and the floating electrode. The pixel
electrode is positioned on the second passivation layer.
At least one of the color filter and the light blocking member may
be positioned on the first passivation layer.
The second passivation layer may have different thicknesses.
A thickness of the second passivation layer positioned in the first
region may be larger than thicknesses of the second passivation
layer positioned in the second region and the third region.
The thickness of the second passivation layer positioned in the
second region may be larger than the thickness of the second
passivation layer positioned in the third region.
In a display device according to one or more embodiments of the
present invention, three regions of a pixel may respectively have
three different electric field magnitudes. Therefore, the pixel may
provide three difference luminance levels. Advantageously, the
display device may be able to display images with satisfactory
visibility (e.g., side visibility). For providing the three
different luminance levels, the pixel may need only one transistor.
Advantageously, a satisfactory aperture ratio may be attained, such
that potential afterimage may be alleviated. Relations among the
three different electric field magnitudes may be optimized though
configuration of distances between electrodes in the pixel.
Advantageously, a response speed and/or image texture control
associated with the display device may be optimized.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic plan view illustrating elements and/or
structures in one pixel area of a display device according to an
embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view taken along line II-II
indicated in FIG. 1 according to an embodiment of the present
invention.
FIG. 3 is a schematic cross-sectional view taken along line III-III
indicated in FIG. 1 according to an embodiment of the present
invention.
FIG. 4 is a schematic plan view illustrating a pixel electrode
according to an embodiment of the present invention.
FIG. 5 is a schematic plan view illustrating a common-voltage
electrode and a floating electrode according to an embodiment of
the present invention.
FIG. 6 is a schematic plan view illustrating a common-voltage
electrode and a floating electrode according to an embodiment of
the present invention.
FIG. 7 is a schematic plan view illustrating a pixel electrode, a
common-voltage electrode, and a floating electrode according to an
embodiment of the present invention.
FIG. 8 is a schematic plan view illustrating a pixel electrode
according to an embodiment of the present invention.
FIG. 9 is a schematic plan view illustrating a pixel electrode, a
common-voltage electrode, and a floating electrode according to an
embodiment of the present invention.
FIG. 10 is a schematic plan view illustrating a pixel electrode
according to an embodiment of the present invention.
FIG. 11 is a schematic plan view illustrating a pixel electrode, a
common-voltage electrode, and a floating electrode according to an
embodiment of the present invention.
FIG. 12A is a schematic cross-sectional view taken along line
III-III indicated in FIG. 1 according to an embodiment of the
present invention.
FIG. 12B is a schematic cross-sectional view taken along line
III-III indicated in FIG. 1 according to an embodiment of the
present invention.
FIG. 12C is a schematic cross-sectional view taken along line
III-III indicated in FIG. 1 according to an embodiment of the
present invention.
FIG. 12D is a schematic cross-sectional view taken along line
III-III indicated in FIG. 1 according to an embodiment of the
present invention.
FIG. 13 illustrates voltage-transmittance (V-T) graphs related to
Examples associated with embodiments of the present invention and
gamma curve graphs related to Comparative Examples.
FIG. 14 illustrates a gamma curve graph related to an Example
associated with an embodiment of the present invention and a gamma
curve graph related to a Comparative Example.
FIG. 15, FIG. 16, and FIG. 17 illustrate pixel images related to
Examples associated with embodiments of the present invention.
FIG. 18A, FIG. 18B, and FIG. 18C illustrate V-T graphs related to
insulating layer thicknesses between electrodes according to
embodiments of the present invention.
FIG. 19 illustrates V-T graphs related to Examples associated with
embodiments of the present invention and V-T graphs related to
Comparative Examples.
DETAILED DESCRIPTION OF EMBODIMENTS
Embodiments of the present invention are described with reference
to the accompanying drawings. As those skilled in the art would
realize, the described embodiments may be modified in various
different ways, all without departing from the spirit or scope of
the present invention.
Although the terms "first", "second", etc. may be used herein to
describe various elements, these elements, should not be limited by
these terms. These terms may be used to distinguish one element
from another element. Thus, a first element discussed below may be
termed a second element without departing from the teachings of the
present invention. The description of an element as a "first"
element may not require or imply the presence of a second element
or other elements. The terms "first", "second", etc. may also be
used herein to differentiate different categories or sets of
elements. For conciseness, the terms "first", "second", etc. may
represent "first-category (or first-set)", "second-category (or
second-set)", etc., respectively.
In the drawings, thicknesses of layers, films, panels, regions,
etc., may be exaggerated for clarity. Like reference numerals may
designate like elements throughout the specification. When a first
element (such as a layer, film, region, or substrate) is referred
to as being "on" a second element, the first element can be
directly on the second element, or one or more intervening elements
may also be present. In contrast, when a first element is referred
to as being "directly on" a second element, there are no intended
intervening elements between the first element and the second
element.
In the description, the term "connect" may mean "electrically
connect"; the term "insulate" may mean "electrically insulate".
FIG. 1 is a schematic plan view illustrating elements and/or
structures in one pixel area of a display device according to an
embodiment of the present invention. FIG. 2 is a schematic
cross-sectional view taken along line II-II indicated in FIG. 1.
FIG. 3 is a schematic cross-sectional view taken along line III-III
indicated in FIG. 1. FIG. 4 is a schematic plan view illustrating a
pixel electrode according to an embodiment of the present
invention. FIG. 5 is a schematic plan view illustrating a
common-voltage electrode and a floating electrode according to an
embodiment of the present invention.
Referring to FIG. 1 and FIG. 2, gate conductors including a gate
line 121 and a gate electrode 124 may be positioned on a first
insulation substrate 110, which may be made of a transparent
material, e.g., one or more of transparent glass, transparent
plastic, etc. The gate electrode 124 may protrude from the gate
line 121. The gate line 121 may include a wide end portion (not
illustrated) for contact with another element, e.g., an element of
a driving circuit.
The gate conductors may be made of at least one of aluminum-based
metals such as aluminum (Al) or an aluminum alloy, silver-based
metals such as silver (Ag) or a silver alloy, copper-based metals
such as copper (Cu) or a copper alloy, molybdenum based metals such
as molybdenum (Mo) or a molybdenum alloy, chromium (Cr), tantalum
(Ta), and titanium (Ti). The gate conductor may have a
multi-layered structure including at least two conductive layers
having different physical properties.
The gate line 121 crosses a plurality of pixel areas in a first
direction, e.g., a horizontal direction.
A gate insulating layer 140 is positioned on the gate conductor.
The gate insulating layer 140 may be made of silicon nitride (SiNx)
and/or silicon oxide (SiOx) and may have a multi-layered structure
including at least two insulating layers having different physical
properties.
A semiconductor layer 154 is positioned on the gate insulating
layer 140. The semiconductor layer 154 overlaps the gate electrode
124 and may be made of at least one of amorphous silicon,
crystalline silicon, etc.
An ohmic contact (not illustrated) may be positioned on the
semiconductor layer 154. No ohmic contact may be needed if the
semiconductor layer 154 is made of an oxide semiconductor.
Data conductors including a data line 171, a source electrode 173,
and a drain electrode 175 may be positioned on the semiconductor
layer 154 and the gate insulating layer 140. The data line 171 may
include a wide end portion (not illustrated) for contact with
another element, e.g., an element of a driving circuit.
The data conductors, the ohmic contact, and the semiconductor layer
154 may be substantially simultaneously formed using a single mask
in a same process.
The data line 171 may transfer a data signal, may extend in a
second direction, e.g., a vertical direction, and may cross the
gate line 121. The above-described first direction and second
direction may be substantially perpendicular to each other.
The source electrode 173 may extend from the data line 171 and may
have a C-shape structure. One or more portions of the drain
electrode 175 may be parallel to one or more portions of the source
electrode 173 and/or may be positioned between two portions of the
source electrode 173. A portion of the drain electrode 175 may
contact a portion of a pixel electrode 191a that extends through a
contact hole 185.
The gate electrode 124, the source electrode 173, and the drain
electrode 175 form a thin film transistor (TFT) together with the
semiconductor layer 154. A channel region of the thin film
transistor is positioned in the semiconductor layer 154 between the
source electrode 173 and the drain electrode 175.
The data conductors may be made of at least a refractory metal,
such as one or more of molybdenum, chromium, tantalum, titanium, an
alloy of two or more of these metals, etc. The data conductors may
have a multi-layered structure (or multilayer structure) including
a refractory metal layer (not illustrated) and a low-resistance
conductive layer (not illustrated).
In an embodiment, the multi-layered structure includes a lower
layer made of chromium or molybdenum (alloy) and includes an upper
layer made of aluminum (alloy). In an embodiment, the multi-layered
structure includes a lower layer made of molybdenum (alloy), an
intermediate layer made of aluminum (alloy), and an upper layer
made of molybdenum (alloy). In an embodiment, the data conductors
may be made of various metals or conductors in addition to or
alternative to the above materials.
A first passivation layer 180p is positioned on the data conductors
171, 173, and 175, the gate insulating layer 140, and an exposed
portion of the semiconductor layer 154. The first passivation layer
180p may be made of at least one of an organic insulating material,
an inorganic insulating material, etc.
A color filter 230 and a light blocking member 220 may be
positioned on the first passivation layer 180p. The color filter
230 may be configured for displaying one of several primary colors,
such as one of red, green, and blue, or yellow, cyan, magenta, etc.
In an embodiment, the color filter 230 may be configured for
displaying a mixed color of primary colors or for displaying
white.
In an embodiment of the present invention, the light blocking
member 220 and the color filter 230 may be positioned on the upper
panel 200. In an embodiment of the present invention, the color
filter 230 and the light blocking member 220 may be positioned on
the lower panel 100 and the upper panel 200, respectively.
A common-voltage electrode 191b and a floating electrode 191c may
be positioned on the color filter 230 and the light blocking member
220. In an embodiment, an overcoat (not illustrated) may be
positioned on the color filter 230 and the light blocking member
220, and the common-voltage electrode 191b and the floating
electrode 191c may be positioned on the overcoat.
Referring to FIG. 5, the common-voltage electrode 191b may include
a plate part 191b1 and may have an opening 191b2. Common-voltage
electrodes 191b positioned in adjacent pixel areas may be
electrically connected to each other. The common-voltage electrodes
191b may be electrically connected to a voltage source and may
receive a common voltage from the voltage source through, for
example, a connection (not illustrated) with another element, e.g.,
an element of a driving circuit.
The common-voltage electrode 191b may include an extended part,
which may extend parallel to an edge of the floating electrode
191c. The floating electrode 191c may be positioned between two
extended portions of the common-voltage electrode 191b.
The floating electrode 191c and the common-voltage electrode 191b
are positioned on the same layer and may be formed in a same
process step. The floating electrode 191c includes cross stem parts
193c and 194c and includes a plurality of fine branch parts 199c
extending from the cross stem parts 193c and 194c. The fine branch
parts 199c may extend in a diagonal direction from the second cross
stem parts 193c and 194c and may extend perpendicular to, parallel
to, or aligned with each other.
The floating electrode 191c is insulated from other constituent
elements, and substantially no voltage may be applied to the
floating electrode 191c, such that the floating electrode 191c may
be electrically floating.
A second passivation layer 180q is positioned on the common-voltage
electrode 191b and the floating electrode 191c. The second
passivation layer 180q may be made of at least one of an organic
insulating material, an inorganic insulating material, etc.
The pixel electrode 191a is positioned on the second passivation
layer 180q. The pixel electrode 191a is connected to the drain
electrode 175 through a contact hole 185 formed in the first
passivation layer 180p, the light blocking member 220, and the
second passivation layer 180q and may receive a data voltage from
the drain electrode 175.
Referring to FIG. 4, the pixel electrode 191a includes cross stem
parts 193a and 194a, fine branch parts 199a extending from the
first cross stem parts 193a and 194a, and a connection part 196a.
The fine branch parts 199a may extend in a diagonal direction from
the cross stem parts 193a and 194a, and may extend orthogonal to,
parallel to, or aligned with each other
The connection part 196a is connected to the cross stem parts 193a
and 194a and/or the first fine branch part 199a at a connection and
may extend from the connection to the contact hole 185. An end of
the connection part 196a is physically and electrically connected
to the drain electrode 175 through the contact hole 185.
The connection part 196a may have a cross shape, as illustrated in
FIG. 1 and/or FIG. 4, and may overlap the cross stem parts 193c and
194c of the floating electrode 191c. In an embodiment, the
connection part 196a may have a structure different from the cross
shape.
According to an embodiment of the present invention, in a first
region R1, a first portion of the pixel electrode 191a (e.g., a
part of the cross stem parts 193a and 194a and a part of the fine
branch parts 199a) may overlap neither of the common-voltage
electrode 191b and the floating electrode 191c in a direction
perpendicular to the pixel electrode 191a and/or perpendicular to
an image display side of the display device. The image display side
of the display device may be an outer side of the panel 200. In a
second region R2, a second portion of the pixel electrode 191a may
overlap the plate part 191b1 of the common-voltage electrode 191b
in the direction, with the second passivation layer 180q being
positioned between the pixel electrode 191a and the common-voltage
electrode 191b. In a third region R3, a third portion of the pixel
electrode 191a (e.g., the connection part 196a) may overlap the
floating electrode 191c in the direction.
The pixel electrode 191a may receive a data voltage through the
contact hole 185 from the drain electrode 175. The common-voltage
electrode 191b may receive a common voltage provided by a voltage
source. The floating electrode 191c may be insulated from other
constituent elements and may be electrically floating without
substantially receiving a supplied voltage.
In an embodiment, the pixel electrode 191a, the common-voltage
electrode 191b, and the floating electrode 191c may provide three
different electric field magnitudes in the first region R1, the
second region R2, and the third region R3, respectively, in
cooperation with a common electrode 270. The common electrode 270
may be electrically connected to the voltage source and/or may
receive the common voltage from the voltage source.
Among the three different magnitudes in the three regions, the
magnitude of the electric field applied to the liquid crystal layer
portion positioned in the first region R1 may be the largest, and a
magnitude of the electric field applied to the liquid crystal layer
portion positioned in the third region R3 may be the smallest. The
magnitude of the electric field applied to the liquid crystal layer
portion positioned in the second region R2 may be smaller than the
magnitude of the electric field applied to the liquid crystal layer
portion positioned in the first region R1 and may be larger than
the magnitude of the electric field applied to the liquid crystal
layer portion positioned in the third region R3.
The common electrode 270 is positioned on a second insulation
substrate 210, which may be made of transparent glass and/or
transparent plastic. The common electrode 270 may substantially
cover a surface of the second insulation substrate 210.
Alignment layers (not illustrated) may be formed on inner surfaces
of the panels 100 and 200 (which may face each other) and may be
vertical alignment layers.
Polarizers (not illustrated) may be disposed on outer surfaces of
the panels 100 and 200. Transmission axes of the two polarizers may
be orthogonal to each other, and one of the transmission axes may
be parallel to the gate line 121. In an embodiment, a polarizer may
be disposed on the outer surface of one of the panels 100 and 200,
and no polarizer may be disposed on the outer surface of the other
one of the panels 100 and 200.
A liquid crystal layer 3 may be positioned between the common
electrode 270 and the pixel electrode 191a. The liquid crystal
layer 3 may have a negative dielectric anisotropy, and liquid
crystal molecules of the liquid crystal layer 3 may be oriented so
that long axes of the liquid crystal molecules are substantially
perpendicular to the panels 100 and 200 when no electric field is
applied to the liquid crystal layer 3.
Incident light may be substantially blocked by the crossed
polarizers when no electric field is applied to the liquid crystal
layer 3.
FIG. 6 is a schematic plan view illustrating a common-voltage
electrode and a floating electrode according to an embodiment of
the present invention. FIG. 7 is a schematic plan view illustrating
a pixel electrode according to an embodiment of the present
invention. FIG. 8 is a schematic plan view illustrating a pixel
electrode according to an embodiment of the present invention. FIG.
9 is a schematic plan view illustrating a pixel electrode according
to an embodiment of the present invention. FIG. 10 is a schematic
plan view illustrating a pixel electrode according to an embodiment
of the present invention. FIG. 11 is a schematic plan view
illustrating a pixel electrode according to an embodiment of the
present invention. FIG. 12A, FIG. 12B, FIG. 12C, and FIG. 12D are
cross-sectional views taken along line III-III indicated in FIG. 1
according to one or more embodiments of the present invention.
Elements discussed with references to one or more of FIG. 6, FIG.
7, FIG. 8, FIG. 9, FIG. 10, FIG. 11, FIG. 12A, FIG. 12B, FIG. 12C,
and FIG. 12D may have features that are identical to or analogous
to one or more of the features discussed above with reference to
FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5. Description of
identical or analogous features may not be repeated.
Referring to FIGS. 6 and 7, the common-voltage electrode 191b may
have slits 199b positioned in the plate part 191b1.
A width of a slit 199b may be equal to a width of a fine branch
part 199a of the pixel electrode 191a and/or a width of a fine
branch part 199c of the floating electrode 191c. In an embodiment,
as illustrated in FIG. 7, a fine branch part 199a of the pixel
electrode 191a may be positioned between two slits 199b of the
common-voltage electrode 191b in a plan view of a pixel of the
display device.
Referring to FIGS. 8 and 9, the connection part 196a of the pixel
electrode 191a may have bar members that enclose a quadrangle space
in a plan view of the display device. The bar members may overlap
end portions of fine branch part 199c of the floating electrode
191c.
The connection part 196a may be connected to the first fine branch
part 199a and the cross stem parts 193a and 194a. A bar member
(e.g., a lower portion of the connection part 196a) may include a
protrusion that extends to be electrically and physically connected
to a drain electrode through a contact hole.
Referring to FIGS. 10 and 11, the connection part 196a of the pixel
electrode 191a may include a cross-shaped structure and bar members
enclosing the cross-shaped structure in a plan view of the display
device. The connection part 109a of the pixel electrode 191a may
have four quadrangular openings in the plan view of the display
device.
The connection part 196a may have bar members overlapping end
portions of fine branch part 199c of the floating electrode 191c
and may have a cross-shaped structure overlapping the cross stem
parts 193c and 194c of the floating electrode 191c.
In various embodiments of the present invention, structures of the
pixel electrode, the common-voltage electrode, and the floating
electrode may be configured to have various shapes for optimizing
the sizes and shapes of the regions R1, R2, and R3. Advantageously,
quality of images displayed by display devices may be
optimized.
FIG. 12A, FIG. 12B, FIG. 12C, and FIG. 12D are cross-sectional
views taken along line III-III indicated in FIG. 1 according to one
or more embodiments of the present invention.
Referring to FIG. 12A, a thickness d2 of a portion the second
passivation layer 180q positioned in the second region R2 (where
the pixel electrode 191a overlaps the common-voltage electrode
191b) may be larger than a thickness d1 of portions of the second
passivation layer 180q positioned in the first region R1 and the
third region R3.
In the second region R2, the pixel electrode 191a may be
sufficiently spaced from the common-voltage electrode 191b by the
thickness d2 of the second passivation layer 180q, such that a
proper voltage ratio may be obtained between the first region R1
and the second region R2. Advantageously, transmittance associated
with the liquid crystal layer 3 may be optimized.
In the third region R3, the small thickness d1 of the second
passivation layer 180q may enable a sufficient capacitance formed
between the floating electrode 191c and (the connection part 196a
of) the pixel electrode 191a. Advantageously, texture control
and/or transmittance associated with the liquid crystal layer 3 of
the display device may be improved.
Referring to FIG. 12B, portions of the second passivation layer
180q positioned in the third region R3 may have different
thicknesses. In an embodiment, the thickness d3 of a portion of the
second passivation layer 180q that is adjacent to the second region
R2 and overlaps the floating electrode 191c may be smaller than the
thickness d2 of a portion of the second passivation layer 180q
positioned in the second region R2 and may be larger than the
thickness d1 of a portion of the second passivation layer 180q
positioned relatively close to the thin film transistor in the
third region R3. The different thicknesses of the second
passivation layer 180q in the region R3 may enable optimization of
visibility associated with imaged displayed by the display device.
In an embodiment, visibility may be optimized by gradually
decreasing or increasing thicknesses of the second passivation
layer 180q in the region R3 from the region R2 toward the thin film
transistor.
Referring to FIG. 12C, portions of the second passivation layer
180q positioned in the second region R2 and positioned between the
electrodes 191a and 191b may have different thicknesses. A first
portion of the second passivation layer 180q in the region R2 may
have a relatively large thickness d2. A second portion of the
second passivation layer 180q between the first portion of the
second portion of the passivation layer 180q and the region R3 may
have a relatively small thickness d1. The different thicknesses of
the second passivation layer 180q in the region R2 may enable
optimization of visibility associated with imaged displayed by the
display device.
Referring to FIG. 12D, a part of the second passivation layer 180q
positioned in the second region R2 (where the pixel electrode 191a
overlaps the common-voltage electrode 191b) may have a relatively
large thickness d2, and a part of the second passivation layer 180q
that overlaps the common-voltage electrode 191b without overlapping
the pixel electrode 191a in a direction perpendicular to the
substrate 110 may have a relatively small thickness d3. A part of
the second passivation layer 180q positioned in the third region R3
may have a relatively small thickness d1, and a part of the second
passivation layer 180q positioned in the third region R3 may have a
relatively large thickness d3. The different thicknesses of the
second passivation layer 180q in the regions R2 and R3 may enable
optimization of visibility associated with imaged displayed by the
display device.
According to embodiments of the present invention, thicknesses of
the second passivation layer 180q may be controlled for controlling
one or more of image visibility, transmittance, texture, etc.
associated with the display device.
The above-described passivation layer having different thicknesses
may be formed using a halftone mask and/or a slit mask. In an
embodiment, an alternative method or an additional method may be
used for forming the passivation layer.
FIG. 13 illustrates voltage-transmittance (V-T) graphs related to
Examples associated with embodiments of the present invention and
gamma curve graphs related to Comparative Examples. Referring to
FIG. 13, it can be seen that V-T (voltage-transmittance) graphs of
Example 1 (common-voltage electrode) and Example 2 (floating
electrode) of the present invention move to the right compared to
Comparative Example 1 and Comparative Example 2. That is, the V-T
curves are delayed.
FIG. 14 illustrates a gamma curve graph related to an Example
associated with an embodiment of the present invention and a gamma
curve graph related to a Comparative Example. Referring to FIG. 14,
the Example associated with an embodiment of the present invention
has a gamma curve closer to an ideal gamma curve than the
Comparative Example. In other words, the Example associated with an
embodiment of the present invention has improved visibility
compared to the Comparative Example.
FIG. 15, FIG. 16, and FIG. 17 illustrate pixel images related to
Examples associated with embodiments of the present invention.
Referring to FIGS. 15 to 17, the pixel electrode is driven at a low
gray (2.8 V). The pixel electrode, the common-voltage electrode and
the floating electrodes are driven at a halftone gray (4.5 V) over
the first region, the second region, and the third region so as to
have different luminance values, and driven at a high gray (8.0 V)
so as to have higher luminance values. Given the different
luminance values at different regions, side visibility of images
may be improved.
FIG. 18A, FIG. 18B, and FIG. 18C illustrate voltage-transmittance
(V-T) graphs related to thicknesses of the second passivation layer
between the pixel electrode and each of the common-voltage
electrode and the floating electrode according to embodiments of
the present invention.
As the thickness of the second passivation layer is reduced at a
position of the common-voltage electrode, transmittance associated
with the display may deteriorate. Transmittance associated with the
display device is improved as the thickness of the second
passivation layer is reduced at a position of the floating
electrode. In other words, the common-voltage electrode and the
floating electrode show opposite characteristics according to the
thickness of the second passivation layer. Therefore, according to
embodiments of the present invention, the second passivation layer
may have different thicknesses in the region where the
common-voltage electrode is positioned and the region where the
floating electrode is positioned. Advantageously, the display
device may have improved transmittance.
FIG. 19 illustrates V-T graphs related to the examples associated
with embodiments of the present invention and V-T graphs related to
the Comparative Examples. Referring to FIG. 19, when the second
passivation layer has a single thickness, an aspect indicated by a
solid line is shown, but different thicknesses are applied to the
regions where the common-voltage electrode and the floating
electrode are positioned, such that optimized visibility may be
provided, as indicated by a dotted line.
According to embodiments of the present invention, each pixel area
of a display device may be divided into three regions that have
different electric field magnitudes. Therefore, each pixel areas
may have different luminance values. Advantageously, the display
device may display images with satisfactory visibility and/or
satisfactory resolution. For providing the three different
luminance levels, the pixel may need only one transistor.
Advantageously, a satisfactory aperture ratio may be attained, such
that potential afterimage may be alleviated. Relations among the
three different electric field magnitudes may be optimized though
configuration of distances between electrodes in the pixel.
Advantageously, a response speed and/or image texture control
associated with the display device may be optimized.
While embodiments of this invention have been described, this
invention is not limited to the described embodiments. This
invention is intended to cover various modifications and equivalent
arrangements included within the spirit and scope of the appended
claims.
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